Stability–Indicating Spectrofluorimetric Methods for the Determination of Metolazone and Xipamide in Their Tablets. Application to Content Uniformity Testing

A highly sensitive, simple and rapid stability-indicating spectrofluorimetric method was developed for the determination of metolazone (MET) and xipamide (XPM) in their tablets. The proposed method is based on the measurement of the native fluorescence of MET in methanol at 437 nm after excitation at 238 nm and XPM in alkaline methanolic solution at 400 nm after excitation at 255 nm. The fluorescence–concentration plots were rectilinear over the range of 2.0– 20.0 ng/mL for MET and 0.2– 2.0 μg/mL for XPM, with lower detection limits (LOD) of 0.35 ng/mL and 0.02 μg/mL and a lower quantification limit (LOQ) of 1.05 ng/mL and 0.07 μg/mL for MET and XPM, respectively. The method was successfully applied to the analysis of MET and XPM in their commercial tablets and the results were in good agreement with those obtained using the official and comparison methods, respectively. Furthermore, content uniformity testing of the studied pharmaceutical tablets was also conducted. The application of the proposed method was extended to stability studies of MET and XPM after exposure to different forced degradation conditions, such as acidic, alkaline, oxidative and photolytic degradation conditions, according to ICH Guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and photolytic degradation of MET. The apparent first-order rate constants and half-life times were calculated. Proposals for the degradation pathways for both MET and XPM were postulated.     

Stability-Indicating Spectrofluorimetric Method for Determination of Itopride Hydrochloride in Raw Material and Pharmaceutical Formulations

A simple, sensitive and rapid spectrofluorimetric method for determination of itopride hydrochloride in raw material and tablets has been developed. The proposed method is based on the measurement of the native fluorescence of the drug in water at 363 nm after excitation at 255 nm. The relative fluorescence intensity-concentration plot was rectilinear over the range of 0.1–2 μg/mL (2.5?×?10^?7–5.06?×?10^?6 mole/L), with good correlation (r?=?0.9999), limit of detection of 0.015 μg/mL and a lower limit of quantification of 0.045 μg/mL. The described method was successfully applied for the determination of itopride hydrochloride in its commercial tablets with average percentage recovery of 100.11?±?0.32 without interference from common excipients. Additionally, the proposed method can be applied for determination of itopride in combined tablets with rabeprazole or pantoprazole without prior separation. The method was extended to stability study of itopride. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and oxidative degradation of the drug. A proposal for the degradation pathways was postulated.     

Micelle-Enhanced Spectrofluorimetric Method for Determination of Cyproheptadine Hydrochloride in Tablets: Application to In-Vitro Drug Release and Content Uniformity Test

A highly sensitive and simple spectrofluorimetric method was developed for the determination of cyproheptadine hydrochloride (CYP) in its pharmaceutical formulations. The proposed method is based on the investigation of the fluorescence spectral behaviour of CYP in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution, the fluorescence intensity of CYP was greatly enhanced (150 %) in the presence of SDS. The fluorescence intensity was measured at 410 nm after excitation at 280 nm. The fluorescence–concentration plot was rectilinear over the range 0.2–2.0 μg/mL, with lower detection limit of 0.06 μg/mL. The proposed method was successfully applied to the assay of commercial tablets as well as content uniformity testing. The application of the proposed method was extended to test the in-vitro drug release of CYP tablets, according to USP guidelines. The results were statistically compared with those obtained by official USP method and were found to be in good agreement.     

Spectrofluorimetric Determination of Terbinafine Hydrochloride and Linezolid in their Dosage Forms and Human Plasma

A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of Terbinafine HCl (TRH) and linezolid (LNZ) in their pharmaceutical formulations. The proposed method is based on measuring the native fluorescence of the studied drugs in water at 336 nm after excitation at 275 nm for TRH and 375 nm after excitation at 254 nm for LNZ. The fluorescence–concentration plots were rectilinear over the range of 0.02–0.15 μg/mL for TRH and 0.5–5.0 μg/mL for LNZ. With lower detection limits of 3.0 and 110.0 ng/mL and a lower quantification limit of 9.0 and 320.0 ng/mL for TRH and LNZ, respectively. The method was successfully applied to the analysis of TRH in its commercial tablets, cream, gel and spray formulations and the results were in good agreement with those obtained with the official method. In addition the method was also applied to the analysis of LNZ in its capsule and I.V solution and the results were in good agreement with those obtained with the comparison method. The effect of sensitizers was studied. The method was extended to the determination of the studied drugs in spiked human plasma and the results were satisfactory.     

Highly Sensitive Synchronous Fluorescence Measurement of Danofloxacin in Pharmaceutical and Milk Samples Using Aluminium (III) Enhanced Fluorescence

A simple, rapid and sensitive constant wavelength synchronous fluorescence method is developed for the determination of danofloxacin (DAN) in pharmaceutical formulations and its residue in milk based on Al(III) enhanced fluorescence. The synchronous fluorescence intensity of the system is measured at 435?nm using ? λ?=?80?nm and an excitation wavelength of 280?nm. A good linear relationship between enhanced fluorescence intensity and DAN concentration is obtained in the range of 3-100?ng?mL(-1)(r (2)?=?0.9991). The limit of detection (LOD, S/N?=?3) of the present method is 0.9?ng?mL(-1). The proposed method can be successfully applied to the determination of DAN in pharmaceutical formulations and in milk without serious interferences from common excipients, metal ions and other co-existing substances. The method can be used as a rapid screening to judge whether the DAN residues in milk exceed Maximum Residue Limits (MRLs) or not.     

Spectrofluorometric Determination of Methocarbamol in Pharmaceutical Preparations and Human Plasma

A simple, sensitive and rapid spectrofluorometric method for determination of methocarbamol in pharmaceutical formulations and spiked human plasma has been developed. The proposed method is based on the measurement of the native fluorescence of methocarbamol in methanol at 313 nm after excitation at 277 nm. The relative fluorescence intensity-concentration plot was rectilinear over the range of 0.05–2.0 μg/mL, with good correlation (r = 0.9999), limit of detection of 0.007 μg/ mL and a lower limit of quantification of 0.022 μg/ mL. The described method was successfully applied for the determination of methocarbamol in its tablets without interference from co-formulated drugs, such as aspirin, diclofenac, paracetamol and ibuprofen, The results obtained were in good agreement with those obtained using the official method (USP 30).The high sensitivity of the method allowed the determination of the studied drug in spiked human plasma with average percentage recovery of 99.42 ± 3.84.     

培氟沙星胶束包合物的荧光特性及应用

提出一种基于胶束增敏测定培氟沙星的荧光分光光度法 ,研究了培氟沙星与十二烷基硫酸钠 (SDS)形成胶束包合物的荧光性质 ,对影响荧光的不同变量和参数进行了研究和优选。试验结果表明 ,在pH 5的BrittonRobinson(BR)缓冲溶液中 ,SDS胶束对培氟沙星有强的增敏作用 ,培氟沙星胶束包合物的激发和发射波长分别为 λex =2 78nm和λem =4 32nm 。其线性范围为 0 0 6～ 1 2 0 μg·mL- 1 ,方法检出限为 0 0 6 μg·mL- 1 ,回收率为 98 5 %～ 10 0 8% ,相对标准偏差为 1 4 %～ 2 3%。该方法已成功用于片剂和血浆中培氟沙星含量的测定 ,其结果令人满意。本文采用同步导数荧光光谱法测定了血浆中的培氟沙星 ,其选择性好 ,灵敏度高 ,可有效地消除血浆中荧光背景的干扰 ,降低了检测限。     

Conventional and First Derivative Synchronous Fluorometric Determination of Ethamsylate in Pharmaceutical Preparations and Biological Fluids. Application to Stability Studies

Two simple, accurate and highly sensitive spectrofluorometric methods were developed for the determination of ethamsylate (ETM). Method I is based on measuring the native fluorescence of ethamsylate in water at 354 nm after excitation at 302 nm. The calibration plot was rectilinear over the range of 0.05–1 μg/mL for ETM with limits of detection and quantitation of 7.9 and 26 ng/mL, respectively. Method II involved synchronous and first derivative synchronous fluorometric methods for the simultaneous determination of ethamsylate (ETM) and hydroquinone (HQ) which is considered as an impurity and/or acidic degradation product. The synchronous fluorescence of both the drug and its impurity were measured in methanol at Δ λ of 40 nm. The peak amplitudes (¹D) were estimated at 293.85 or 334.17 nm for ETM and at 309.05 nm for HQ. Good linearity was obtained for ETM over the ranges 0.1–1.4 μg/mL and 0.1–1.0 μg/mL at 293.85 and 334.17 nm, respectively. For HQ, the calibration plot was rectilinear over the range of 0.01–0.14 μg/mL at 309.05 nm. Limits of detection were 20, 2.01 ng/mL and limits of quantitation were 60, 6.7 ng/mL for ETM and HQ by method II, respectively. Both methods were successfully applied to commercial ampoules and tablets. The results were in good agreement with those obtained by the reference method. Method I was utilized to study the stability of ETM and its degradation kinetics using peroxide. The apparent first-order rate constant, half-life times and activation energy of the degradation process were calculated. Method I was further extended to the in-vitro and in-vivo determination of ETM in spiked and real plasma samples. The mean% recoveries were 99.57 ± 3.85 and 89.39 ± 5.93 for spiked and real human plasma, respectively.     

Micelle-Enhanced Spectrofluorimetric Method for Determination of Cholesterol-Reducing Drug Ezetimibe in Dosage Forms

A simple and sensitive spectrofluorimetric method was developed for the determination of ezetimibe in its pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behavior of ezetimibe in sodium dodecyl sulfate (SDS) micellar system. In aqueous solution of acetate buffer pH 5.0, the fluorescence intensity of ezetimibe was greatly enhanced, 200% enhancement, in the presence of SDS. The fluorescence intensity of ezetimibe was measured at 380 nm after excitation at 268 nm. The fluorescence-concentration plot was rectilinear over the range of 0.03–3.0 μg/mL with lower detection limit of 3.08 × 10⁻³ μg/mL. The method was successfully applied to the analysis of ezetimibe in its commercial tablets; the results were in good agreement with those obtained with the reported method. The application of the proposed method was extended to the stability studies of ezetimibe after exposure to different forced degradation conditions, such as acidic, alkaline, photo and oxidative conditions, according to ICH guidelines.     

Spectrofluorimetric Determination of Famotidine in Pharmaceutical Preparations and Biological Fluids. Application to Stability Studies

A simple, economic, selective, and stability indicating spectrofluorimetric method was developed for the determination of famotidine (FMT); is based on its reaction with 9, 10-phenanthraquinone in alkaline medium to give a highly fluorescent derivative measured at 560 nm after excitation at 283 nm. The fluorescence intensity - concentration plot was rectilinear over the concentration range of 50–600 ng/ml with minimum quantification limit (LOQ) of 13.0 ng/ml and minimum detection limit (LOD) of 4.3 ng/ml. The factors affecting the development of the fluorescence intensity of the reaction product were carefully studied and optimized. The method was applied for the determination of FMT in its dosage forms. The stability of the compound was studied, and the proposed method was found to be stability indicating one. The results obtained were in good agreement with those obtained by the official method. Furthermore, the method was applied for the determination of FMT in spiked and real human plasma. The mean % recovery (n = 4) was found to be 99.94 ± 0.24, and 105.13 ± 0.64 for spiked and real human plasma, respectively. The composition of the reaction product as well as its stability constant was also investigated. Moreover, the method was utilized to investigate the kinetics of both alkaline and oxidative induced degradation of the drug. The apparent first order rate constant and half life time of the degradation product was calculated. A proposal of the reaction pathway was postulated.     

阿霉素与DNA作用的共振光散射研究及在DNA分析中的应用

研究了抗癌药物阿霉素与DNA相互作用的吸收光谱、荧光光谱和共振光散射光谱,发现阿霉素与DNA相互作用产生强烈增强的共振光散射信号,共振光散射技术在研究DNA与阿霉素的相互作用时,其灵敏度远远高于吸收光谱和荧光光谱。DNA与阿霉素作用在322与564 nm处产生两个共振散射峰,在弱酸性条件下(pH 5.72),DNA的浓度在0～8.0 μg·mL-1范围内与散射强度呈良好的线性关系,对小牛胸腺DNA和鱼精子DNA的检出限分别为36.8和40.1 ng·mL-1。由此建立了一种选择性好,灵敏度高的DNA共振光散射分析方法。     

诺氟沙星的荧光光谱研究及其应用

采用荧光光谱法研究了诺氟沙星在不同pH条件下的光谱行为,发现诺氟沙星在pH 3.04的水溶液中具有较强的荧光发射,与中性介质相比荧光发射光谱红移了30 nm。据此分别建立了药物制剂中和人体尿液中诺氟沙星的荧光光谱法和同步-导数荧光光谱法。经样品测定,其线性范围为0.016～0.96 μg·mL-1,检出限为0.016 μg·mL-1, 回收率为99.7%～100.94%, 相对标准偏差为1.65%～2.86%。     

β-环糊精交联树脂富集-氢化物发生原子荧光光谱法测定水中的三苯基锡

提出利用β-环糊精交联树脂分离富集环境水样中的三苯基锡并结合氢化物发生原子荧光光谱法,对其消解物进行定量分析的新方法,通过实验优化其化学和仪器条件,方法灵敏度高、精密度好,检出限为0.1 ng·mL-1,相对标准偏差RSD为2.64%(0.04μg·mL-1),成功地用于实际水样中三苯基锡的分析.     

催化荧光法测定痕量亚硝酸根

在稀磷酸介质中 ,溴酸钾可氧化吖啶橙使之褪色并伴随着吖啶橙荧光强度的减弱 ,但反应速率较慢。痕量亚硝酸根的存在对该反应可起到显著的催化作用 ,使反应的灵敏度明显提高 ,体系的荧光猝灭程度加强。基于此采用固定时间法提出了一种灵敏度高、选择性好的催化荧光法测定痕量亚硝酸根的新方法 ,并研究了该方法的动力学条件。催化反应在λex/λem =4 4 6 / 5 0 5nm处 ,5 5℃水浴中进行 10min。反应可允许较大量的 2 0多种常见离子存在 ,同倍量的Fe3 ,Br-、I-不干扰。亚硝酸根的线性范围为 0 0 5～ 5ng·mL-1,方法的检出限为 0 0 12ng·mL-1。用于水体和土壤中痕量亚硝酸根的测定 ,结果满意。     

稀土铽离子与去甲肾上腺素的荧光反应及其分析应用

实验发现稀土铽离子能与去甲肾上腺素发生络合反应 ,并发射出铽离子的特征荧光。在对铽离子与去甲肾上腺素的络合发光反应进行了详细研究的基础上 ,提出了一种简便、快速、灵敏检测去甲肾上腺素的新方法。在激发波长为 30 0nm ,发射波长为 5 4 5nm处测定其荧光强度 ,去甲肾上腺素浓度在 0 0 1～ 5 0 μg·mL-1范围内与体系的荧光强度具有良好的线性关系 ,相关系数为 0 9990 ,检出限为 1 0ng·mL-1(S/N=3)。该法应用于去甲肾上腺素药物的测定 ,结果令人满意。     

Simple and Sensitive Spectrofluorimetric Method for the Determination of Oseltamivir Phosphate in Capsules Through Derivatization with Fluorescamine

A new, simple and sensitive spectrofluorimetric method has been developed for the determination of oseltamivir phosphate (OSP) in capsules. The method is based on the reaction between oseltamivir and fluorescamine in borate buffer solution of pH 8.50 to give highly fluorescent derivatives that are measured at 483 nm using an excitation wavelength of 381. The different experimental parameters effecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence intensity concentration plot is rectilinear over the range 50–450 ng mL⁻¹ with a lower detection limit (LOD) of 1.219 ng mL⁻¹ and limit of quantitation (LOQ) of 4.064 ng mL⁻¹. Selectivity was validated by subjecting stock solution of OSP to acidic, basic, oxidative, and thermal degradation. No interference was observed from excipients present in formulations. The developed method was successfully applied to determination of the drug in capsules. The mean % recovery (n = 6) was 100.08. The results obtained were in good agreement with those obtained using a reported spectrophotometric method.     

微波消化冷原子荧光法测定鲨鱼肝脏中的汞

研究了冷原子荧光法测定鲨鱼肝脏中汞的工作条件。样品风干后在2 mol·L-1 HNO₃-4 mol·L-1 HCl体系中以V₂O₅为催化剂,微波消解样品,上清液中的汞被SnCl₂还原后于253.7 nm(激发光)用冷原子荧光法测定,线性范围0～0.2 ng·mL-1,r=0.999 7,检出限为0.05 ng·mL-1,相对标准偏差0.86%～2.22%,平均回收率在96.0%～108.5%,该法简便、快速、准确。     

[Cu(DPPZ)(L-Ser)]+与DNA的相互作用及其分析应用研究

研究了DNA与铜(Ⅱ)-L丝氨酸-二吡啶并[3,2-a:2',3'-c]吩嗪配合物[Cu(DPPZ)(L-Ser)-]+相互作用的共振光散射光谱和紫外可见吸收光谱,通过研究体系与溴化乙啶相互作用的荧光光谱特征,证明其作用方式为插入作用.在pH 7.2的缓冲溶液中,[Cu(DPPZ)(L-Ser)]+由于插入作用而在DNA表面聚集,使体系的共振光散射强度增强,最大敞射峰在400 nm处.在最佳实验条件下,共振光散射增强的强度与浓度在0.42～4.20 ng·mL1范围的DNA具有良好的线性关系.方法的检出限为0.29 ng·mL-1.该法用于DNA样品的测定,回收率在97.8%～106.0%之间.     

树脂分离-氢化物发生-原子荧光光谱法测定中草药中不同形态的砷

本文建立了应用离子交换树脂分离技术结合氢化物发生 原子荧光光谱法测定中草药方剂原生药、残渣、悬浮态及可溶态中的三价及五价砷的方法。研究了树脂静态分离和动态分离的最佳条件 ,利用两种方法成功地对黄连解毒汤中的三价及五价砷进行了分离。考察了仪器的工作条件、试剂浓度、增感剂的选择及共存离子的干扰及消除方法。方法检出限为 89 1ng·L- 1 ,RSD为 1 4 % ,样品加标回收率为 91 1%～10 9 3%。     

银纳米微粒荧光猝灭法测定水中痕量ClO2

在pH 9.1的NH4Cl-NH3·H2O缓冲溶液中,银纳米微粒在470 nm处产生一个荧光峰;它能被ClO2氧化导致体系的荧光发生猝灭.ClO2浓度在0.001 1～0.185μg·mL-1范围内与荧光猝灭强度成良好的线性关系,检测限为0.004 7μg·mL-1 ClO2.据此建立了测定ClO2的荧光分析新方法,用于饮用水中ClO2的测定,结果满意.